Ionic polymers are polymers containing ionic groups as parts of the main chain or laterally thereof. Depending on the ion content, they may be divided into polyelectrolytes and ionomers. Polyelectrolytes have a high percentage ion content and are generally soluble in water, examples being polymethacrylic acid or polyacrylic acid. By contrast, ionomers are generally insoluble in water on account of their largely apolar main chain and their relatively small content of ionic groups. Known ionomers are polyacrylates, polyurethanes and, in particular, thermoplastic copolymers of ethylene with carboxyfunctional monomers, particularly methacrylic acid, which are partly present as salts of sodium, potassium, magnesium or zinc. By virtue of the ionic bond, they are thermo-reversibly crosslinked. They are used, for example, as films for packaging and coating materials and inter alia as self-adhesive films.
It is also known to the expert that carboxyl-group-stabilized dispersions (anionic dispersions) can readily coagulate in contact with polyvalent dissolved cations (for example Ca.sup.2+, Zn.sup.2+, Al.sup.3+, etc.) because insoluble carboxylate salts eliminate the emulsifier effect. This principle is used to improve dispersions containing carboxyl groups in the water resistance and non-tackiness of the films by complexed Zn or Zr ions after drying and evaporation of the ligand (see, for example, EP 0 197 662, DE 23 37 606, DE 38 00 984). Accordingly, ion-compatible dispersions are generally cationically or nonionically stabilized.
In addition, it is known from works of Matsuda and Kothandaraman (see, for example, H. Matsuda, Journal of Polymer Science 12, 455-468 (1974); H. Kothandaraman, Polymer Bulletin 13, 353-356 (1985)) that special short-chain OH-terminated compounds containing a carboxyl group prepared in solvents change their properties, for example their melting point, by dimerization with divalent salts. After dissolution in organic solvents, these solids bridged by polyvalent ions can be reacted with aromatic or aliphatic diisocyanates to form glass-like polymers.
However, there is no document in the prior art which describes oligomers processable in particular at room temperature to give useful performance properties simply by linking individual fat- and oil-based oligomer structural units by salt bridges of polyvalent ions.
Hitherto, the need for ecologically safer products in such fields as sealants, coatings (for example lacquers and paints), adhesives, plastics processing and fire prevention, which has arisen out of the increase in environmental awareness, has only been partly satisfied. Both organic solvents and residual monomers or chlorine-containing polymers have to be replaced by alternative systems. Thus, polymers dissolved in organic solvents have been increasingly replaced, for example, by aqueous polymer dispersions in the past few decades. Products such as these cure or set through evaporation of the liquid phase which can or does give rise to a considerable shrinkage in volume and, in the case of water-based systems, to a marked dependence of the drying time on climatic conditions.
In addition to systems which already contain preformed polymers to establish the final properties, there are also reactive systems based on monomers or oligomers which cure by chemical reaction of 1 or 2 components. Cyanoacrylates, NCO-terminated polyurethanes, which set or crosslink under the effect of moisture, or 2-component epoxides and polyurethanes are well known to the expert. Like 1-component reactive systems, 2-component product formulations consisting of resin and catalyst often contain highly reactive, toxicologically unsafe monomers or residual monomers or form unwanted decomposition products in use--a fact which generally has to be communicated to the consumer by warnings (on labels).
Advantages of reactive systems include, for example, their relatively low starting viscosity (the high molecular weight polymers are only formed during the curing process) and the possibility of obtaining 100% systems with no significant shrinkage in volume. It would be extremely desirable to utilize the advantages of known 1- and 2-component reactive systems, but at the same time to be able to resort to toxicologically safer and environmentally more compatible starting monomers or oligomers.